Video and other types of media are increasingly being delivered over the Internet and other networks, in a form of media streams utilising standardised packet formats, such as the Real-time Transport Protocol (RTP) developed by the Internet Engineering Task Force (IETF), and defined in RFC 3550. RTP provides end-to-end network transport functions that are suitable for applications transmitting real-time data, such as audio, video or simulating data, over multicast or unicast network services. RTP is augmented by a control protocol, called Real-time Control Protocol (RTCP), to allow monitoring of the data delivery in a manner that is scalable to large multicast networks, and to provide minimal control and identification functionality.
It is well known for media services, such as video streaming and the like, to be provided to different types of media terminals, ranging from mobile devices, such as mobile telephone handsets, to desktop computers etc. As will be appreciated by a skilled artisan, due to the varying capabilities and requirements of media terminals and their respective communication paths, it is typically the case that different mobile terminals have different media requirements. Examples of such differing media requirements for video streaming may include, for example, encoding requirements, frame rate requirements, bit rate requirements, frame size requirements, etc.
In order to enable the provision of media services to different media terminals having differing media requirements, without the need to provide a duplicate of each service for every combination of media requirement, it is known to use apparatus such as gateways through which media terminals may access media services. In this manner, the gateway processes received media streams and converts them into the required formats for each media terminal accessing the media services there through.
Thus, a gateway is required to be able to process a plurality of simultaneous media streams, each stream comprising packets of data arriving asynchronously. Furthermore, the gateway is required to maximise the channel density for media frames processed thereby, whilst minimising the latency of the media streams through the gateway so that each packet is processed and the result output within a period that is less than a delay threshold.
In order to improve the processing of media content, it is known to prioritise the processing of media frames based on their deadlines by which they are required to be processed; media frames generally having the most imminent deadlines by which they are required to be processed are processed first. Typically, such deadlines are based on a time limit within which a frame is required to be processed following the receipt of the first data packet of that frame. In this manner, fewer media frames will tend to be dropped as a result of them not being processed by their deadline, thus improving the channel density of received media streams.
U.S. Pat. No. 6,975,629, titled ‘Processing packets based on deadline intervals’, describes a mechanism whereby first and second data packets are prioritized using deadline intervals of each data packet. This patent teaches a mechanism whereby the data packet with the closest deadline is scheduled first.
However, such known techniques fail to take into account other considerations, such as data type, processing requirements etc. Consequently, such known techniques fall short of optimising the channel density for each media stream, whilst minimising the latency of the media streams through the gateway.
Thus, a need exists for an improved method and apparatus for scheduling a processing of packet stream channels, such as media stream channels.